Wrong Billing.

I have an explora and connected one dstv on compact I normally pay R459 and last month I added an insurance for my explora and the amount was R489 but month end they debited R505.94 and when I phoned they admitted it was an error but when I go to self service my next months payment is R624 which means I will paying for 2 access fees of which I only have one, this means this is an ongoing error (wrong Billing) and how are we going to be compensated for being overcharged.